This invention relates to a network termination of a telecommunications network having at least one interface on the network side and both analog and digital interfaces on the subscriber-line side.
A telecommunications network, particularly a telephone network, commonly comprises a number of exchanges that are connected with one another. A plurality of terminals are connected to each exchange. At the interface between each terminal and the telecommunications network, a network termination is provided.
FIG. 1 illustrates how the design of a network termination has changed in the course of time. FIG. 1a shows a network termination for an all-analog telecommunications network. The network termination NT has an analog interface a/b on the network side and an analog interface a/b on the subscriber-line side. Via the analog interface on the subscriber-line side, the terminal can connect an end instrument END, such as an analog telephone, to the telecommunications network.
FIG. 1b shows a network termination for an all-digital telecommunications network. The network termination NT has a digital interface U on the network side and a digital interface S on the subscriber-line side. Via the digital interface on the subscriber-line side, the terminal can connect an end instrument END, such as a digital telephone, to the telecommunications network.
FIG. 1c shows a network termination for an integrated services digital network (ISDN). The network termination NT has a digital interface U on the network side and two digital interfaces S1, S2 on the subscriber-line side. Via the digital interface S1, the terminal can connect a digital end instrument END1, e.g., a digital telephone or a PC, to the telecommunications network, and via the digital interface S2, it can additionally connect an analog end instrument END2, e.g., an analog telephone, using a terminal adapter TA. In the so-called basic access configuration, two 64-kb/s B channels are available to a terminal, which can be used independently of each other. For example, a telephone conversation can be conducted via the interface S2, and at the same time, Internet surfing is possible via the interface S1.
FIG. 1d also shows a network termination for an integrated services digital network, but here, the terminal adapter is incorporated in the network termination, so that analog end instruments END2, such as an analog telephone, can be connected directly to the network termination NT. This network termination NT thus offers maximum freedom of access on the subscriber-line side but has the disadvantage that on the network side, access is required to a digital telecommunications network, such as the ISDN. As a result; a subscriber wishing to operate only an analog end instrument has to pay an unduly high charge for being connected to a digital line.
The network termination shown in FIG. 1d corresponds in design and operation to the network termination NTtwin+, which is described in more detail in the Alcatel prospectus “Alcatel 1581 ID, NTtwin+, ISDN BRA NT1+2ab equipment, Technical Description” and in the Alcatel folder “Alcatel 1581 ID, NTtwin+, The bridge to a new technology”.